Combination terminal and fuse holder arrangement for an electrical circuit

ABSTRACT

A combined terminal and fuse holder arrangement utilized in an electrical circuit, such as an open coil heater assembly. The terminal includes an insulator which supports a projecting arm having an aperture to receive a screw. The end of a circuit element is formed in a loop to hook about the body of the screw, the screw holding the element in electrical connection with the arm. The arm is bridged electrically through a fuse to a terminal contact which is also supported by the insulator.

United States Patent 119 Ammerman et a1.

COMBINATION TERMINAL AND FUSE HOLDER ARRANGEMENT FOR AN ELECTRICALCIRCUIT Inventors: George Edward Ammerman;

' William McFarlane, both of Murfreesboro, Tenn Assignee: Heatcraft,Inc., Murfreesboro,

Tenn.

Filed: May 3, 1972 Appl. No.: 249,791

US. Cl 337/237, 219/517, 337/231, 1 337/235, 337/253 Int. Cl. HOlh 85/16Field of Search 219/517, 532, 523, 253, 219/541, 536; 337/202, 203, 231,237, 235, 253, 9, 181

References Cited UNITED STATES PATENTS l/l949 Harlow 337/9 1451 Mar. 26,1974 2,211,520 8/1940 Smith .Q. 219/517 x FOREIGN PATENTS ORAPPLICATIONS 743,205 1/1933 France 337/181 Primary Examiner-Bernard A.Gilheany Assistant Examiner-Fred E. Bell Attorney, Agent, orFirmCushman, Darby & Cushman 5 7] ABSTRACT A combined terminal and fuseholder arrangement utilized in an electrical circuit, such as an opencoil heater assembly. The terminal includes an insulator which supportsa projecting arm having an aperture to receive a screw. The end of acircuit element is formed in a loop to hook about the body of the screw,the screw holding the element in electrical connection with the arm. Thearm is bridged electrically through a fuse to a terminal contact whichis also supported by the insulator.

4 Claims, 4 Drawing Figures The invention generally relates to animproved construction for servicing a fused electrical circuit, such asan open coil heater assembly. In such assemblies, fuses frequentlyrequire replacement. Conventionally, the fuse is connected in thecircuit such that the entire heater assembly must be removed from itsoperative position and the fuse replaced by breaking one or moremechanical connections, removing the defective fuse, attaching the newfuse in place, and relocating the entire assembly in its operativeposition. Such steps are inconvenient and costly.

In an effort to avoid entire assembly removal, heater assemblies havebeen developed which utilize separate terminals for supporting the fuseand the heater coil. Besides being uneconomical, such arrangementssuffer the further shortcoming of occupying considerable space on thebase plate of the assembly and requiring a jumper from one terminal tothe other. These factors are of substantial importance in multicoilassemblies which usually include control elements, such as relays andtemperature responsive devices, the proper positioning of which iscomplicated by the presence of a considerable number of terminals. I

Briefly, the invention relates to the latter type of system wherein theentire assembly need not be removed but wherein the number of terminalsis reduced and replacement of defective parts is facilitated bycombining the fuse supporting and coil end holding functions in a singleterminal. The terminal includes an insulator for supporting an arm whichprojects towards the heating coil. The arm has an aperture for receivinga screw, and the end of the heating coil loops about the screw and iselectrically connected to the arm when the screw is tightened. A fuseelectrically bridges the arm to a terminal contact which also issupported by the insulator.

The invention will be described in further detail by reference to theaccompanying drawings, wherein:

FIG. 1 illustrates a conventional prior art arrangement for connecting afuse and a coil in an open coil heating assembly, the arrangement beingof the type in which the entire heating assembly need not be removedfrom its operative position in order to replace the fuse;

FIG. 2 is an elevational view of an open coil heating element assemblyincorporating the present invention;

FIG. 3 is an elevational view of the assembly taken at 90 to that viewshown in FIG. 2; and

FIG. 4 is a view in section of the insulator portion of the terminaltaken along line 4-4 of FIG. 3.

Referring to FIG. I, there is disclosed a known mannor of securing afuse and a heater coil end in an open coil heater assembly. A plateserves as a base for supporting a pair of terminals having insulators I2and l4. Insulator 12 is a two-piece construction held together by ascrew 16 passing along the axes of the pieces and cooperating with apair of nuts 18. The heater coil 20 is soldered to the head of screw 16.Insulator 14 is connected to the base plate by means of a screw 22passing through an ear 24 projecting from the insulator. A pair ofcontacts 26 and 28 are provided at one end of insulator l4, and arms 30and 32 project from the opposite end. Contact 26 and arm 30 are inelectrical connection as are contact 28 and arm 32. A fuse 34 bridgesarms 30 and 32, and the fuse is electrically joined to coil 20 by ajumper 36 joined between contact 28 and the screw 16. The nuts 18 securethe 5 jumper in electrical contact with the screw.

With the arrangement just described, it is often the practice inreplacing the fuse to discard the entire insulator-fuse assembly (14,34) in favor of a new one. This constitutes an economical disadvantagefor the FIG. 1 arrangement.

However, more important than the expense of replacing the several partsin the arrangement of FIG. 1 is the serious disadvantage of their takingup a substantial amount of space on the surface of base plate 10. Thenecessity of two terminals hinders the placement on the base plate ofother important components of an open coil heater system such as relays,temperature responsive devices, etc. The problem increases as the numberof heater coils becomes greater.

The shortcomings of prior art systems are overcome by the presentinvention as disclosed in FIGS. 24. Referring to FIGS. 2 and 3, there isillustrated the base plate 10 and support structure, generally indicatedas 40, for the open coil heater 20. The support structu e, which isfully described in US. Pat. No. 3,641,312 granted on Feb. 8, 1972, formsno part of the present invention.

A single terminal is used to support a fuse 34 and the end of heatercoil 20. The terminal includes an insulator which is preferably ceramicformed with an exterior shoulder 44 (FIG. 4) which abuts the base plate10 when the insulator is properly positioned to project through anaperture in the base plate. The insulator includes an car 46 throughwhich a screw 48 extends to secure the insulator 42 to the base plate.

The interior of the insulator 42 is provided with passages (FIG. 4) toreceive electrically conductive elements. One of these elements is anarm 50 which has a U-shaped cross-section; Arm 50 abuts an internalshoulder 52 formed within a first passage 54, and coextensive with arm50 is a projection 56 having ears 58 which are bent to engage the outersurface of insulator 42 thereby maintaining arm 50 in fixed positionwith respect to the insulator. Similarly, a shorter arm 60 abutsshoulder 62 formed within a second passage 64. Coextensive with arm 60is a projection 66 which extends beyond the insulator 42 to serve as acontact 68. Again, arm 60 is held in fixed position by ears 70 whichengage the outer surface of insulator 42.

A fuse 34 has its ends attached to arms 50 and 60. The flat surface ofthe U-shaped arm 50 is provided with an aperture to receive a screw 72.The end of coil 20 is bent in a loop 74 to be hooked about the body ofscrew 72 so that when the screw is tightened, an electrical circuit isassured from contact 68, through projection 66, arm 60, fuse 34 and arm50 to the heater coil 20.

Preferably the end of loop 74 of the heater coil is arranged to extendbeyond the end of arm 50. Thus, when a fuse is found defective, thescrew 48 is undone to permit the insulator 42 to be disconnected frombase plate 10. The insulator is then withdrawn from the base plateagainst the spring tension of coil 20. At a point when the loop 74projects through the aperture in base plate 10, the loop end is hookedon the surface of the base plate. The screw 72 is then disconnected toseparate the coil 20 from the insulator assembly. A new assembly canthen be substituted and the coil attached thereto by means of screw 72.When the loop end of coil is unhooked from the base plate, the springtension snaps the insulator into place against the base plate, where itis firmly affixed by screw 48.

From the foregoing it can be appreciated that the invention resides in astructural arrangement for a combination fuse holder and terminal for anelectrical circuit employing a single element which is attached to abase plate. The arrangement disclosed permits ease of replacement ofcomponents and occupies much less space than conventional replaceablefuse holder arrangements. While the embodiment shown is that used for asingle coil, it should be appreciated that the insulator 42, whichcomprises a principal part of the terminal, may be formed withadditional passages so as to permit termination of plural circuits in amanner such as that just described for a single circuit.

What is claimed is:

l. A combined terminal and fuse holder adapted to project through anaperture of a supporting plate associated with an electrical circuitarrangement, such as an open coil heater assembly, comprising:

I an insulator element havinga pair of passages extending therethrough;

a first arm positioned within one of said passages and having anelectrical contact extending beyond one side of the insulator element;

a second arm positioned within the other of said passages and projectingbeyond the opposite side of the element;

a fuse connected between the projecting portion of said second arm andsaid first arm to complete an electrical path from the contact throughsaid first passage and the fuse to said projecting portion of the secondarm;

means for securing said arms within their respective passages, saidsecuring means for at least the second arm including fastening meansintegral with said arm and engaging a surface of the insulator elementto hold said arm in fixed position within its passage with a portion ofthe arm abutting a shoulder defined by the passage internally of saidelement; and

means on the projecting portion of the second arm for removably securingan end of said electrical circuit to said arm whereby the terminal andfuse holder are separated from the circuit arrangement when the end ofsaid circuit is disconnected from said second arm.

2. A combined terminal and fuse holder as set forth in claim 1, whereinsaid fastening means includes cars bent to engage said insulator elementsurface.

3. In an electrical circuit assembly, a combined terminal and holder fora thermal fuse adapted to project through an aperture of a supportingplate associated with said electrical circuit to removably locate saidfuse adjacent to and in thermally operative relationship with a secondarm joined to said insulator element and projecting beyond the oppositeside of the element whereby said second arm is accessible from theopposite side of the plate;

said thermal fuse being positioned on the opposite side of the elementand connected between the projecting portion of the second arm and saidfirst arm; and

means on the projecting portion of the second arm for removably securingan end of said electrical circuit to said arm whereby the terminal andfuse holder are separated from the circuit arrangement when the end ofsaid circuit is disconnected from said second arm.

4. In an electrical circuit assembly as set forth in claim 3, thecombined terminal and fuse holder further comprising:

an additional passage extending through said insulator element anddefining a shoulder internal of said element, the second arm beingpositioned within said additional passage; and

fastening means integral with said second arm and engaging a surface ofthe insulator element to join said arm to the element by holding saidarm in fixed position within its associated passage with a portion ofthe arm abutting the internal shoulder.

1. A combined terminal and fuse holder adapted to project through anaperture of a supporting plate associated with an electrical circuitarrangement, such as an open coil heater assembly, comprising: aninsulator element having a pair of passages extending therethrough; afirst arm positioned within one of said passages and having anelectrical contact extending beyond one side of the insulator element; asecond arm positioned within the other of said passages and projectingbeyond the opposite side of the element; a fuse connected between theprojecting portion of said second arm and said first arm to complete anelectrical path from the contact through said first passage and the fuseto said projecting portion of the second arm; means for securing saidarms within their respective passages, said securing means for at leastthe second arm including fastening means integral with said arm andengaging a surface of the insulator element to hold said arm in fixedposition within its passage with a portion of the arm abutting ashoulder defined by the passage internally of said element; and means onthe projecting portion of the second arm for removably securing an endof said electrical circuit to said arm whereby the terminal and fuseholder are separated from the circuit arrangement when the end of saidcircuit is disconnected from said second arm.
 2. A combined terminal andfuse holder as set forth in claim 1, wherein said fastening meansincludes ears bent to engage said insulator element surface.
 3. In anelectrical circuit assembly, a combined terminal and holder for athermal fuse adapted to project through an aperture of a supportingplate associated with said electrical circuit to removably locate saidfuse adjacent to and in thermally operative relationship with saidcircuit, the combined terminal and fuse holder comprising: an insulatorelement adapted to be removably secured to said plate and to projectthrough said aperture, said insulator having a passage extendingtherethrough; a first arm positioned within said passage, said armhaving an electrical contact extending beyond one side of the insulatorelement to permit access thereto from one side of the plate; a secondarm joined to said insulator element and projecting beyond the oppositeside of the element whereby said second arm is accessible from theopposite side of the plate; said thermal fuse being positioned on theopposite side of the element and connected between the projectingportion of the second arm and said first arm; and means on theprojecting portion of the second arm for removably securing an end ofsaid electrical circuit to said arm whereby the terminal and fuse holderare separated from the circuit arrangement when the end of said circuitis disconnected from said second arm.
 4. In an electrical circuitassembly as set forth in claim 3, the combined terminal and fuse holderfurther comprising: an additional passage extending through saidinsulator element and defining a shoulder internal of said element, thesecond arm being positioned within said additional passage; andfastening means integral with said second arm and engaging a surface ofthe insulator element to join said arm to the element by holding saidarm in fixed position within its associated passage with a portion ofthe arm abutting the internal shoulder.